Timeline - Earthquakes
An interactive look at some of the historical aspects of Earthquakes. Find out more about these unpredictable forces by browsing or searching the Science Learning Hub.
- A discovery by Robert Hooke
Robert Hooke realised that earthquakes are connected to land movements.
- Modern studies begin
A huge earthquake and tsunami in Portugal killed over 70,000 people. This marked the start of modern earthquake studies, as people began to collect data to help understand the events.
- Electromagnetic seismograph invented
Luigi Palmieri invented the first accurate electromagnetic seismograph, which could detect earthquakes not felt by humans.
- Seismic waves discovered
Robert Mallet realised that most earthquake damage is due to moving waves caused by a sudden land movement, named seismic waves.
- Layer of rocks discovery
John Pratt and George Airy suggested that surface rocks float on a layer of denser rock.
- Fault lines proposition
Grove Gilbert figured out that earthquakes are centred around fault lines.
- Seismometer detection
For the first time, a seismometer (in Germany) detected an earthquake on the other side of the Earth (in Japan).
- P-waves and S-waves
Richard Oldham realised that there were at least two types of seismic waves that travelled at different speeds. We know these now as P-waves and S-waves.
- Atomic reactions
Ernest Rutherford claimed that the Earth is heated by atomic reactions.
- New thinking about fault lines
After the most destructive earthquake in American history at San Francisco, Harry Reid suggested that earthquakes are the result of stresses built up along faults.
- Probing inside the Earth
Andrija Mohorovicic realised that you could use seismic waves to probe the hidden Earth.
- Continental drift
Alfred Wegener put forward the idea of continental drift. His theory was that the continents were once joined to form a giant supercontinent that he called Pangaea.
- 7,000km at the core
Beno Gutenberg used seismic waves to estimate the diameter of the Earth’s core as 7,000 kilometres – a size that is still thought to be correct.
- Colliding supercontinents
Alexander du Toit suggested that mountains are formed by colliding continents. He also suggested that Pangaea divided into two supercontinents. He called the northern supercontinent Laurasia and the southern one Gondwana.
- Convection and continental drift
Harry Hess proposed convection currents in the mantle as a mechanism for continental drift.
- How much damage?
Guiseppe Mercalli created the Modified Mercalli Scale to measure earthquake damage, based on a scale originally made in 1902.
- Measuring magnitude
Charles Richter and Beno Gutenberg developed a new magnitude scale for earthquakes, now known as the Richter Scale.
- P-waves measure inner core
Inge Lehmann used data from P-waves to suggest the existence of an inner core to the Earth.
- Monitoring earthquakes worldwide
A worldwide earthquake monitoring system was set up. Several systems now exist, including the Global Seismographic Network. They contribute to the understanding of plate tectonics and other Earth processes.
- Plate tectonics
The realisation that ocean floors behave differently to continents led to the theory of plate tectonics.
- Discovering slow slips
First slow slip events noticed in Japan and Canada. These are helping to explain plate movement and stress build-up in subduction zones.
- Inner core movement
Xiaodong Song and Paul Richards, using P-waves, discovered that the solid inner core rotates freely within the fluid outer core and at a different speed to the rest of the Earth.
- New Zealand’s slow slip
First slow slip events recorded in New Zealand.